/usr/share/glib-2.0/schemas/10_gnome-system-log.gschema.override is in gnome-system-log 3.9.90-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | [org.gnome.gnome-system-log]
logfile='/var/log/syslog'
logfiles=['/var/log/auth.log', '/var/log/dpkg.log', '/var/log/mail.log', '/var/log/syslog', '/var/log/Xorg.0.log']
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